A 2-year-old boy in China had surgery to “give birth” after doctors discovered the undeveloped fetus of his twin brother inside his swollen stomach.

According to the Daily Mail, Xiao Feng was brought to the hospital when his stomach became distended and he experienced trouble breathing.

After performing a series of MRI scans and X-rays on the boy, doctors discovered that he was suffering from an extremely rare case of cryptodidymus, or conjoined twins, which is when an undeveloped parasitic twin is concealed within the body of the other twin. Conjoined twins are a result of a fertilized egg failing to separate completely.

Feng had emergency surgery to remove the fetus, which was 10 inches in width and had a fully formed spine and limbs.

According to the Inquisitr, the parasitic twin took up two-thirds of Feng’s stomach and would have led to Feng’s death if doctors had not discovered what was happening.

As the Huffington Post points out, the case is not without precedent. Last year in Peru, doctors operated on a 3-year-old boy who was carrying his parasitic twin brother in his stomach. In 2008, a 9-year-old girl in Greece also had surgery after suffering from the same bizarre condition.

Below, see footage from Chinese media of Xiao Feng and his parasitic twin.